Electro-optical reader with hands-free and hand-held modes of operation

ABSTRACT

An optical scan module, for example for an optical scanner, includes an integrally molded plastics material member which defines not only the laser focusing lens, but also the laser focusing aperture and the collection mirror. In addition, the molded member may act to house and to locate both a semiconductor laser and a photodetector, thereby ensuring easy and accurate placement of those elements within the scanning assembly. The optical assembly may be in modular form, mounted onto a common printed circuit board with a beam scanner.

RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.09/048,418, filed Mar. 26, 1998 now U.S. Pat. No. 6,114,721, which is acontinuation-in-part of U.S. patent application Ser. No. 08/727,944,filed Oct. 9, 1996.

BACKGROUND OF THE INVENTION Field of the Invention

The field of the invention relates to electro-optical readers orscanning systems, such as bar code symbol readers, and more particularlyto a scanning module for use in applications requiring particularlycompact scanners.

DESCRIPTION OF THE RELATED ART

Electro-optical readers, such as bar code symbol readers, are now verycommon. Typically, a bar code symbol comprises one or more rows of lightand dark regions, typically in the form of rectangles. The widths of thedark regions, i.e., the bars, and/or the widths of the light regions,i.e., the spaces, between the bars indicate encoded information to beread.

A bar code symbol reader illuminates the symbol and senses lightreflected from the coded regions to detect the widths and spacings ofthe coded regions and derive the encoded information. Bar code readingtype data input systems improve the efficiency and accuracy of datainput for a wide variety of applications. The ease of data input in suchsystems facilitates more frequent and detailed data input, for exampleto provide efficient inventories, tracking of work in progress, etc. Toachieve these advantages, however, users or employees must be willing toconsistently use the readers. The readers therefore must be easy andconvenient to operate.

A variety of scanning systems are known. One particularly advantageoustype of reader is an optical scanner which scans a beam of light, suchas a laser beam, across the symbols. Laser scanner systems andcomponents of the type exemplified by U.S. Pat. Nos. 4,387,297 and4,760,248—which are owned by the assignee of the instant invention andare incorporated by reference herein—have generally been designed toread indicia having parts of different light reflectivity, i.e., barcode symbols, particularly of the Universal Product Code (UPC) type, ata certain working range or reading distance from a hand-held orstationary scanner.

A variety of mirror and motor configurations can be used to move thebeam in a desired scanning pattern. For example, U.S. Pat. No. 4,251,798discloses a rotating polygon having a planar mirror at each side, eachmirror tracing a scan line across the symbol. U.S. Pat. Nos. 4,387,297and 4,409,470 both employ a planar mirror which is repetitively andreciprocally driven in alternate circumferential directions about adrive shaft on which the mirror is mounted. U.S. Pat. No. 4,816,660discloses a multi-mirror construction composed of a generally concavemirror portion and a generally planar mirror portion. The multi-mirrorconstruction is repetitively reciprocally driven in alternativecircumferential directions about a drive shaft on which the multi-mirrorconstruction is mounted. All of the above-mentioned U.S. Patents areincorporated herein by reference.

In electro-optical scanners of the type discussed above, the “scanengine” including the laser source, the optics the mirror structure, thedrive to oscillate the mirror structure, the photodetector, and theassociated signal processing and decoding circuitry all add size andweight to the scanner. In applications involving protracted use, a largeheavy hand-held scanner can produce user fatigue. When use of thescanner produces fatigue or is in some other way inconvenient, the useris reluctant to operate the scanner. Any reluctance to consistently usethe scanner defeats the data gathering purposes for which such bar codesystems are intended. Also, a need exists for compact scanners to fitinto small compact devices, such as notebooks.

Thus, an ongoing objective of bar code reader development is tominiaturize the reader as much as possible, and a need still exists tofurther reduce the size and weight of the scan engine and to provide aparticularly convenient to use scanner. The mass of the movingcomponents should be as low as possible to minimize the power requiredto produce the scanning movement.

It is also desirable to modularize the scan engine so that a particularmodule can be used in a variety of different scanners. A need exists,however, to develop a particularly compact, lightweight module whichcontains all the necessary scanner components.

SUMMARY OF THE INVENTION

Objects of the Invention

It is an object of the present invention to reduce the size and weightof components used to produce scanning motion of the light beam, and tocollect the reflected light.

A related object is to develop an electro-optical scanning system whichis both smaller and lighter in weight.

It is yet a further object to produce a module which may be manufacturedconveniently, and at low cost. A related object is to provide a modulewhich may be assembled easily.

FEATURES OF THE INVENTION

According to the present invention there is provided an optical scanmodule comprising:

(a) a light source for emitting a light beam;

(b) a scanning assembly for receiving said light beam and for generatingtherefrom a scanning beam directed to an indicia to be read;

(c) a photodetector; and

(d) a one-piece optical element including:

(i) a beam-shaping lens for receiving and shaping said light beam priorto transmission to said scanning assembly; and

(ii) a mirror-defining portion for locating a mirror surface, saidmirror surface being arranged to receive reflected light from saidindicia and to direct it to said photodetector.

Preferably, the one-piece or integral optical element may be molded froman optically transparent plastics material which is selectively coatedto provide the collection mirror reflective surface. The molded membermay also define mounting and/or location portions for the lightsource/laser and/or the photodetector. The photodetector mountingportion may also be coated, preferably with the same material that isused to coat the collection mirror, so as to provide not only opticalbut also electromagnetic shielding for the photodetector.

The molded member may include downwardly-extending “snaps”, allowing themember, along with the mounted laser and photodetector, easily to besecured to an underlying PCB.

Also on the same PCB may be mounted a beam scanning arrangementproviding either linear or two-dimensional scanning.

According to the invention there is further provided an optical scanmodule comprising a mounting base defining a reference plane and havingmounted thereon;

a) a light source for emitting a light beam;

b) a scanning assembly for receiving said light beam and for generatingtherefrom a scanning beam directed to an indicia to be read in whichsaid module is arranged such that the scanning beam defines a scanningplane which is non-orthogonal to the reference plane.

Accordingly the module can be placed on a mother board without the needof spacers to achieve a desired angle.

In another form the invention provides an optical scan module comprisinga base defining a reference plane, a beam reflecting element and a beamreflecting element drive, in which the beam reflecting element ismounted relative to the base to be driven to oscillate in a plane angledto a plane orthogonal to the reference plane.

According to the invention there is further provided a small-sizeoptical scan module comprising a substantially rectangular module base,and mounted thereon a light source for emitting a light beam, a scanningassembly for receiving said light beam and for generating therefrom ascanning beam directed to an indicia to be read, a detector, and a onepiece optical clement including a beam shaping lens for receiving andshaping said light beam prior to transmission to said scanning assemblyand a mirror defining portion for locating a mirror surface, said mirrorsurface being arranged to received retro-reflected light and to directit to said detector.

The invention further provides an optical scan module comprising a lightsource for emitting a light beam, a first scanning assembly forreceiving said light beam and for generating therefrom a scanning beamin a first scanning plane; a second scanning assembly for receiving saidscanning beam from said first scanning assembly and for generating ascanning beam also scanning in a second plane non-parallel to the firstscanning plane; and a detector for detecting a returning beam in whichthe light source, the scanning assembly and the detector are provided ona single module base. Accordingly two dimensional scanning is achievedallowing customised scan patterns.

According to the invention there is further provided a scanning elementfor an optical scanner, the scanning element including a reflector forreflecting a scanning beam and a drive for driving the reflector in ascanning motion in which the reflector is mounted on a torsionallydefinable element and is driven in a scanning motion thereon, and inwhich the torsionally deformable element is elongate, deformable aboutits elongate axis, and non-planar in cross sectional shape perpendicularto its elongate axis, said cross sectional shape being selected toprovide substantially uniform torsional deformation along the elongateaxis.

The invention also provides an optical reader comprising a readerhousing, and a reading beam generator, a reading beam detector and areading beam window mounted in the housing, the housing comprising abase, a handle and a head portion, including the reading window, mountedat one end of the handle, the handle being attached at its other end tothe base, in which the reader is free-standing on the base. An improvedergonomic including hands-free free-standing and hand-held use is thusachieved.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.Further features of the invention are set out in the appendedindependent claims, and further preferred features are set out in thedependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially sectioned view of an optical assembly according tothe preferred embodiment of the invention;

FIG. 2a shows a side view of a gun-type scanner suitable for use withthe optical assembly of FIG. 1;

FIG. 2b is a front view of the scanner of FIG. 2a;

FIG. 2c is a plan view of the scanner of FIG. 2a;

FIG. 2d is an exemplary hand-held optical scanner, suitable for use withthe optical assembly of FIG. 1;

FIG. 2e is an exemplary hand-held combined computer terminal and opticalscanner, again suitable for use with the optical assembly of FIG. 1;

FIG. 3 shows an optical assembly from which a scanning beam exists at anon-90° angle;

FIG. 4 is a flow chart showing operation of the scanner of FIGS. 2a-2 c;

FIG. 5a shows a think flexible band drive of known type;

FIG. 5b shows an improved think flexible band;

FIG. 6 is an exploded view showing mounting of the thin flexible band ofFIG. 5b;

FIG. 7 shows the components set out in FIG. 6 in assembled form;

FIG. 8 shows an optical assembly in a housing in cut-away from;

FIG. 9 show a 2D scan motion scanner assembly;

FIG. 10 is a schematic plan view corresponding to FIG. 9;

FIG. 11 show an alternative scan assembly configuration;

FIG. 12 is an end view corresponding to FIG. 11;

FIG. 13a illustrates the scanning plane in a conventional assembly;

FIG. 13b illustrates he scanning plane in an assembly of the type shownin FIG. 11; and

FIG. 14 shows an alternative scan module housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a low-cost optical assembly, according to the preferredembodiment, for creating a scanning laser beam.

The optical assembly comprises two essentially separate portions, the“static optics” 10 and the scanner motor drive 12, both mounted to acommon printed circuit board (PCB) 14. Before the structure of theassembly is described in detail, it may be helpful to provide a briefoverview of the operation of the device. The light beam 16 from asemi-conductor laser 18 passes through a molded plastics lens 20 and isturned through 90° by total internal reflection from a prism 22. Afterexiting the prism, the beam passes through an aperture 24 in a collectormirror 26, and impinges onto an oscillating scanning mirror 28. Thisproduces a scanning outgoing light beam 30, which is directed toward anindicia (not shown) to be read.

Reflected light 32 from the indicia is first received by the scanningmirror 28, which directs it onto a concave surface 34 of the collectormirror 36. This focuses the light via an aperture 36 and a filter 38onto a photodetector 40. The photodetector output signal is then passedon to suitable electronics within the PCB 14 by an electrical coupling42.

The scanning mirror 28 is mounted at 44 for oscillation about an axis,this being achieved by virtue of the interaction between a permanentmagnet 46 and a driven electromagnetic coil 48. A suitable drivingsignal is applied to the coil, via the PCB 14 and coil electricalcontact 50.

The scanner motor drive 12 shown in FIG. 1 is exemplary, and may bereplaced with any type of mechanism for effecting a scanning motion ofthe laser beam in one or two dimensions. For example, the scanner motordrive could comprise any of the configurations disclosed in U.S. Pat.Nos. 5,581,067 and 5,367,151, all of which are incorporated byreference. In this way, the static optics assembly 10 may be used as acomponent in a variety of scanner designs.

The optical assembly shown in FIG. 1 may be incorporated within any typeof fixed or portable optical scanner, for example the scan-type scannerof FIGS. 2a-2 c the hand-held scanner shown in FIG. 2d or the hand-heldcomputer terminal/scanner shown in FIG. 2e.

Referring to FIGS. 2a to 2 c a hand-held, gun-type scanner of ergonomicdesign is shown. The scanner includes a scanner body designatedgenerated 100 including a handle portion 102 and a head portion 104. Thehandle portion 102 is configured to be held upright in the user's palmand has a forward portion including a trigger 106 positioned preferablyto be operable by the user's forefinger. The head portion 104 isprovided at the top of the handle portion 102 and includes a front faceincluding a scanning window 108 and a bulbous rear portion extendingrearwardly from the handle 102 to rest on or above the user's hand inuse.

The scanner 100 is pivotably fixed to a base portion 110 about a pivotaxis 112 provided at the lower end of the handle 102. The base includesa flat bottom face 114 and extends outwardly from the handle portionboth forward and rear and to the sides such that the assembly as a wholecan be placed freestanding stably on a supporting surface. The scanner100 is arranged to pivot on the base 110 in the forward/backwarddirection. The base 100 provides an interface between the scanner 100and a host (not shown) by a cable 116. The cable 116 can simply carrypower or can also include a data path either for control information tobe passed to the scanner or for data read to be downloaded to the hostfrom the scanner 100.

The base 110 includes on its underside 114 a pressure switch of anysuitable known type (not shown) release of which indicates to aprocessor in the scanner that the scanner is being operated in hand-heldmode. Accordingly the scanner switches to triggered mode indicating thatreading will only take place when trigger 106 is activated.

The control system is illustrated in more detail in the flow chart ofFIG. 4. It will be seen that a continuous loop is maintained by asuitable controller establishing whether or not the pressure switch isactivated (step 150). If the pressure switch is deactivated thentriggered (hand-held) mode is entered (step 152); further discussion ofrelevant features may be found in U.S. Pat. No. 5,151,581, incorporatedherein by reference.

In the alternative mode, where the pressure switch is activated,continuous scanning (hand free) mode 154 is entered. In this mode apresentation scan pattern is always activated allowing all items to passin front of the scanner to be scanned. This can be used for example at aretail sales point such as a check-out stand. Accordingly thearrangement allows dual mode operation.

The scanner is preferably an omni-direction scanner but the gun-typeconfiguration provides the benefits of a conventional one-dimensionalscanner. In addition the adjustable angle provided by the incorporationof a pivot axis 112 allows the scanner as a whole to be positioned atany desired pivot angle for ease of reading and also allows the base tobe angled to a comfortable position when in hand-held mode.

The main body 100 and base 110 are preferably modular such that one orother components can be changed at minimum expense to arrive at, forexample, a cordless embodiment. Optionally a mode button 118 isadditionally provided on the upper face of the head 104 (see FIG. 2c)allowing the user to select a scanning pattern of any desired type forexample based on the bar code symbols or other indicia to be read, orthe scanning conditions. In addition indicator lights such as LED's areprovided at 120 which can indicate, for example, the mode of operationof the scanner, whether it is in hands-free or hand-held mode, and soforth.

Referring now to FIG. 2d, reference numeral 210 generally identifies ahand-held scanner in an alternative embodiment. The scanner mayalternatively be gun-shaped, or any suitable configuration may be used.The scanner is manually-operable for example by a trigger (not shown).As known from the above-identified patents and applications incorporatedby reference herein, a light source component, typically but notnecessarily a laser, is mounted inside the scanner shown at block 210.The light source emits a light beam along a transmission path whichextends outwardly through a window 218 that faces indicia, e.g. bar codesymbols, to be read. Also mounted within the block 210 is aphotodetector component, e.g. a photodiode, having a field of view, andoperative for collecting reflected light returning through the window214 along a path from the symbol.

The optical assembly of FIG. 1 is mounted within or as part of the block210.

In whichever scanner type the arrangement is provided, operation isgenerally the same. The photodetector generates an electrical analogsignal indicative of the variable intensity of the reflected light. Thisanalog signal is converted into a digital signal by an analog-to-digitalconverter circuit. This digital signal is decoded by a decode module222. The decode module 222 decodes the digital signal into datadescriptive of the symbol. An external host device 224, usually acomputer, serves mainly as a data storage in which the data generated bythe decode module 222 is stored for subsequent processing.

The block 210 and decoder 222 are mounted on a PCB 214.

In operation, each time a user wishes to have a symbol read, the useraims the scanner at the symbol and pulls the trigger or otherwiseinitiates reading of the symbol. The trigger is an electrical switchthat actuates the drive means. The symbol is repetitively scanned aplurality of times per second, e.g. more than 100 times per second. Assoon as the symbol has been successfully decoded and read, the scanningaction is automatically terminated, thereby enabling the scanner to bedirected to the next symbol to be read in its respective turn.

In addition, the head need not be a portable hand-held type as fixedlymounted heads are also contemplated in this invention. Furthermore, theheads may have manually operated triggers, or may be continuouslyoperated by direct connection to an electrical source.

The oscillations need only last a second or so, since the multipleoscillations, rather than time, increase the probability of getting asuccessful decode for a symbol, even a poorly printed one. Theresonating reflector has a predetermined, predictable, known, generallyuniform, angular speed for increased system reliability.

Turning now to FIG. 2e, there is shown an alternative hand-held opticalscanner including additional features, this time taking the form of ascanning terminal 326. The terminal comprises a hand-held case 328having a data display screen 30 and a data input keypad 332. The opticalassembly of FIG. 1, within the case 328, produces a scanning light beamwhich extends outwardly through a window 334 which faces the indicia tobe read. Light reflected from the indicia passes back through the window334 and impinges on the photodetector component, for example aphotodiode, which creates a returning light output signal. Theinformation content within that signal may be stored in an on-boardmemory (not shown) or may be downloaded to a remote computer via a dataport 336. Alternatively, the information may be transmitted via a radiofrequency signal produced by an on-board radio transmitter/receiver 338.

In one embodiment the motor drive used to obtain scanning action ispreferably a “taut band element” drive. This type of drive is fullydescribed in, inter alia, U.S. Pat. Nos. 5,614,706 and 5,665,954 whichare commonly assigned herewith and incorporated herein by reference. Inessence, the arrangement includes an optical element such as alightweight mirror mounted on a thin flexible strip (the “taut band”)mounted across an electromagnetic coil. A permanent magnet is attachedto the optical element which interacts with a varying magnetic fieldcreated when an AC signal is applied to the coil to cause repetitivetorsional motion in the flexible strip. As a result the optical elementoscillates providing scanning motion.

FIG. 5a shows a taut band element drive of known type in more detail. Inparticular coil 70, flexible strip 72, mirror 74 and permanent magnet 76can be seen. The flexible strip 72 can be held against the coil 70 forexample by a holding annulus 78. An AC voltage applied to the coil isrepresented schematically at 80 and causes torsional oscillationrepresented schematically by arrow 82. It will be apparent that thisarrangement can replace the arrangement shown generally in FIG. 1 asmirror 28 and drive arrangement 44,46,48 in a manner apparent to theskilled reader.

In a further embodiment shown in FIG. 5b the flexible strip 72 isreplaced by an elongate element 84 which is V-shaped in cross-sectionperpendicular to its elongate axis on which is mounted the mirror 74 andpermanent magnet element 76. The V-shaped element 84 extends across acoil or is otherwise appropriately mounted in the same manner asprevious thin flexible element 72 and the permanent magnet 76 interactswith the AC magnetic field resulting in torsional deflection representedby arrow 86. The V-shaped cross section of the band increases itsstiffness and in particular ensures that the torsional deflection isuniform or substantially uniform over the length of the band, the mirror74 being mounted on the apex of the “V”. It will be appreciated thatalternative configurations for the band cross section can becontemplated such as X shaped, I or H shaped, W shaped as long as therequirements of torsional deflection and uniformity of that torsionaldeflection along the length of the band are maintained.

FIG. 6 shows in exploded form a practical mode of mounting the V-shapedelement 84 of FIG. 5b. Coil 70 is mounted on an E-configuration core 71a including a central arm 71 b which is received in the central recessof the coil 70 and outer arms 71 c and 71 d which extend either side ofthe coil and above it. A mounting plate 75 a is received on the outerarm 71 c,71 d of the E-core and extends above and across the coil 70.The mounting plate 75 a includes a central aperture 75 b defining thespace across which the V-shaped element 84 extends. The V-shaped element84 includes limbs 84 a extending either side of its longitudinal axissymmetrically at either end and the centre and is mounted on themounting plate 75 a across the aperture 75 b in any suitable manner, forexample by securing the end limbs 84 a to the upper face of the mountingplace 75 a. Cooperatingly configured V-shaped connecting elements 85 aresecured to the V-shaped element 84 and generally aligned with the limbs84 a and the mirror 74 is mounted on the connecting elements 85 at theapex of the V-shaped element. Depending from the mirror 74 is a yoke 73also substantially of V-shaped but straddling the V-shaped element 84,having its outer ends 73 a,73 b attached to the rear of the mirror 74.The yoke 73 has a central portion which extends away from the mirror 74and has lateral tabs 73 c,73 d. The lateral tabs 73 c and 73 d are inregister with the central limbs 84 a,84 b of the V-shaped is element andare attached thereto. The permanent magnet 76 is attached to theunderside of the central portion of the yoke 73 for example to theunderside of the tabs 73 c and 73 d. Accordingly the yoke 73 straddlesthe V-shaped element 84 such that the permanent magnet projects over orthrough the aperture 75 b in the mounting plate 75 a allowing optimummagnetic coupling with the Coil 70. When an AC current is applied to thecoil 70 the permanent magnet 76 oscillates which in turn gives rise totorsional flexing of the V-shaped element 84 and oscillation of themirror 74. The assembled arrangement is shown in FIG. 7.

An assembled module incorporating the arrangement of FIG. 7 is shown inFIG. 8 in which it will be seen that a substantially cuboidal housing isincorporated. The direction of angular motion of the mirror is depictedby arrow A.

Alternatively the type of motor drive used to oscillate the scan mirrorcan be a “mylar motor” for example of the unbalanced type as discussedbelow in relation to FIGS. 11-12 according to which the mirror ismounted to a mylar leaf spring which flexes back and forth as thepermanent magnet is driven by the AC coil imparting oscillating motion.Yet a further alternative is a micro machine mirror as discussed in theintroduction in relation to U.S. Pat. Nos. 4,387,297 and 4,409,470according to which the mirror is driven back and forth directly by asuitable drive motor, preferably of very small dimension. Yet a furtheralternative is to use a mirror of known rotating polygon type asdiscussed in the introduction in relation of U.S. Pat. No. 4,251,798according to which the mirror comprises a solid body having a pluralityof face angled to one another. As the body rotates the beam is scannedby successive rotating faces of the polygon body. In one embodiment themylar motor can be used in an arrangement for one dimensional scanningwhilst a V-shaped taut band element (described above) can be used fortwo dimensional scanning also as discussed in more detail below.

Turning now to the static optics assembly 10 shown in FIG. 1, it will benoted that the laser focusing lens 20, the laser aperture 24 and thecollection mirror 26 are all defined by a single molded plasticsmaterial member, shown in cross-hatching and indicated generally by thereference numeral 52. The molded member 52 further acts to house and tolocate the laser 18, the filter 38 and the photodetector 40.

The preferred laser 18 is a semiconductor laser, and preferably an SMD(“surface mounted device”) photodiode. This eliminates the need forphotodiode standoffs and hand-soldering or sockets, as are used on priorart scanners. Typically, the laser will be a standard packagededge-emitting laser. For minimum cost, the laser focusing is notadjustable, and the laser is simply installed with its mounting flangein contact with a shoulder molded as part of the molded member. Thiswill position the laser accurately enough with respect to the moldedfocusing lens 20 to provide adequate performance within an inexpensivescanner. The fact that the focusing lens is molded as part of the samecomponent as the shoulder 54 minimises tolerance build-ups that couldotherwise cause improper focusing.

The laser is held in place within the molded member 52 by means ofUV-curing cement. Since the plastics material of the molded member istransparent to UV light, the cement may be cured by shining UV lightthrough the member into the cavity within which the laser is positioned.Cement may be applied to the laser 18, or to the molded member 52, withthe laser then being pushed into the cavity until it abuts thepositioning shoulder 54. The assembly may then be exposed to ultravioletlight for a few seconds, so curing the cement. If desired for higherperformance, this method of retaining the laser also allows for afocusing adjustment to be made. In this case, the laser is graduallyslid into the cavity while the output beam is being monitored. Whencorrect focus is achieved, the assembly is exposed to UV light, thuscuring the cement and locking the assembly into place.

In the unadjusted assembly, it may be possible to eliminate the cementby spring-loading the laser up against the positioning shoulder 54, forexample by means of a rubber or foam washer 56 between the PCB 14 andthe bottom of the laser 18.

As shown in the drawing, the laser 18 has dowardly-extending electricalleads 58 which are simply installed directly into the PCB 14. Thiseliminates hand-soldering, but soldering could be used if desired.

The fact that the leads extend downwardly into the circuit board meansthat in a conventional laser, the beam will be directly upwardlyperpendicular to the board. The prism 22, previously described, ismolded into the top of the molded member 52 to direct the vertical laserbeam through the aperture 24 in the collector mirror 26 towards thescanning mirror 28. The prism 22 uses total internal reflection toreflect the laser beam, so it is not necessary to coat the upper surfacewith a reflective coating.

To provide for further focusing of the laser beam, should it be desired,it would also be possible to shape the exit surface 60 of the prism.

It is desirable that, somewhere along its path, the laser beam shouldpass through a beam stop. The aperture 24 in the collector mirror 26 mayserve this purpose. Alternatively, the lens 20 or the reflecting or exitsurface of the prism 22 could provide the beam stop.

In fact it is preferred to keep the aperture 24 as small as possiblewhich improves the collection capability of the collector mirror 26. Forexample the aperture 24 may be in the region of 0.5 mm in diameter. Thisprovides an additional advantage as the resulting diffraction patterngives rise to a light distribution following a Bessel function which isparticularly well adapted for scanning indicia.

The molded member 52 needs to be secured to the circuit board 14, and tothat end snaps 62,64 are provided. These automatically latch onto thecircuit board when the component is installed. Alternatively, posts onthe lower side of the molded member may protrude through the board to beheat-staked onto the bottom of the board. Ultrasonic staking could alsobe used.

The collector mirror 26 is coated with a reflective coating so thatlight impinging upon it will be reflected downwardly toward thephotodetector 40. This coating may also cover that part 62 of the moldedmember that serves as a housing for the photodiode. This will render theoptics assembly opaque in that area to prevent any light from reachingthe photodiode except via the aperture 36 and the filter 38.

This reflective coating may also serve another function. Typically, thecoating will be a thin film of metal such as gold, aluminum or chrome.These films are electrically conductive. Accordingly, the film also actsas an electromagnetic interference shield for the photodiode 40. The useof a surface coating to protect the photodiode enables the usual EMIshield to be dispensed with, thereby eliminating both the cost of aseparate shield and the labor to have it installed within the assembly.

The coating is electrically grounded by extending a projection 66 of themolded member into a small socket 68 in the PCB. Alternatively, theprojection 66 could be press-fitted into a plated through-hole in theboard.

The housing portion 62 of the molded member 52 not only acts to hold theoptical filter 38 in place on top of the photodiode 40, but alsoentirely surrounds the photodiode, thereby preventing stray light fromreaching it. The aperture 36 in the housing may be small to limit thefield of view of the detector, maximising ambient light immunity. Theaperture needs to be accurately located with respect to the collectormirror 26, to allow the use of a minimum-sized field of view. Accuraterelative positions of the aperture and the collector mirror are easilyachieved since they are molded as a single part.

An alternative arrangement is shown in FIG. 3. In certain circumstancesit is desired to provide an arrangement in which the beam 30 leaves theoptical assembly at an angle other than 90° to the vertical (relative tothe PCB 14). For example there may be instances in which the mountingrequirements mean that the PCB 14 is mounted at a non-orthogonalposition. In previous arrangements it has been necessary to overcomethis problem by introducing additional spacers when mounting the PCB 14such that the beam 30 leaves at the desired angle. This problem issolved in the arrangement according to FIG. 3 by adjusting the angle bywhich the beam exits the optical assembly to compensate for the mountingangle and remove the need to mount the PCB including a spacer. In thearrangement shown this is achieved by altering the angle of the scanningmirror assembly 28, which is of particular benefit as no adjustment ofthe laser mounting would be required. It will be appreciated that theremaining optics may also require adjustment to further compensate whichadjustments can be easily achieved by the person skilled in the art.

The angle involved is dependent on the particular consumer requirementsbut may be in the region of 45-90° to the PC board, more preferably inthe range of 60-70° and most preferably 65° to the PCB.

FIGS. 11 and 12 show an alternative optical assembly and motor driveembodiment to FIG. 3 according to an embodiment of the invention. Thearrangement is mounted on a single base board 500 and includes a laserassembly 502 of suitable type for example of the type discussed above. Abeam from the laser assembly 502 passes through an aperture 504 in acollector mirror 506 and is reflected by a scanning mirror 508. Thereturning beam is retroreflected onto the collector mirror 506 anddirected to a detector of suitable known type 510. Turning now to thedrive assembly for the scanning mirror 508 in more detail the mirror ismounted in conjunction with a permanent magnet 512 which interacts witha magnetic field provided by an AC current driven coil 514 to oscillatethe mirror. The mirror is mounted relative to the base 500 via anattachment element 501 which is connected to the mirror by two mylarsprings 518,520. Although the mirror is mounted parallel to the base theattachment element 516 is mounted at 25° to the horizontal base and themylar springs which extend perpendicular to the attachment strip 516 arehence at 25° to the vertical. Accordingly a scanning plane is defined at25° to the vertical as discussed in more detail below. It will beappreciated, of course, that any appropriate angle can be selected. Thescan angle is then defined by the amplitude of motion of the mirror andis preferably selected to be 50°. The mirror is of the unbalanced type,that is, no counterweights are provided against the mirror mass.

It will be seen that the mirror 508 is angled relative to the verticalto direct the scanning beam out of the upper face of the assembly. Aswith FIG. 1 although the mirror 508 is represented in FIG. 11 as beingalso angled out of a plane orthogonal with a plane of the paper, this ismerely a drawing representation to render the figure, clearer. It willbe seen that the attachment element 516 includes limbs 522 and 524extending either side of the mylar springs 518,520. These limbs arepositioned within shaped recesses in side blocks 526,528 allowing acertain amount of clearance for the limbs which provides adequate spacefor the desired scanning angle to be achieved whilst providing stops tolimit the amount of oscillation of the mirror should a shock be impartedto the unit for example by dropping it.

Accordingly a beam emitted by the laser assembly 502 incident on themirror 508 is swept through an angle of 50° by the scanning mirror,however the plane of sweep of the beam (the scan plane) is not at 90° tothe base 500 but is at an angle constrained by the direction in whichthe magnet is driven to oscillate i.e. the axis of flexing of the mylarsprings. This can be best be understood with reference to FIGS. 13a and13 b. In FIG. 13a the laser beam 30 enters in the Y direction. Themirror and drive assembly are not shown but in FIG. 13a the normalmirror configuration is assumed that is the mirror is angled at 45° tothe X Z plane and is mounted to oscillate about the X direction. As aresult a scan plane 530 is established in the Y Z plane. However in FIG.13b the mirror and mirror drive are mounted as discussed in relation toFIGS. 11 and 12. It will be seen, therefore, that the scan line isobtained in a plane 532 at 25° to the Y Z plane. Again, any desired scanplane angle or scanning angle can be selected.

Accordingly a non-90° output angle of the beam as discussed in relationto FIG. 3 is achieved in a different manner.

FIG. 9 shows a second preferred embodiment in which two-dimensionalscanning motion is achieved by using two mirrors each oscillating in anorthogonal claim. Multi-pattern scanners can be achieved by using tworeflector X-Y motion as described in U.S. Pat. No. 5,581,070, U.S. Pat.No. 5,637,856 and U.S. Pat. No. 5,614,706 all of which are incorporatedherein by reference. Preferably the two reflectors are driven by a thinflexible element-type drive of the type shown in FIG. 5a or FIG. 7. Inparticular the optical module 10 emits a beam 30 through aperture 24 incollector 34 which is oscillated in a first direction for example the Xdirection by a first oscillating mirror 28 a mounted on a first V-shapedelement 84 and is then oscillated in a second direction for example theY direction by a second mirror 28 b mounted on a V-shaped band 84. As aresult any desired scanning pattern can be achieved at the target asrepresented schematically by pattern 11. All of the elements arepreferably provided in a single module as can be seen from the base layout depicted in FIG. 10. In particular laser 18 emits an outgoing beam30 through an aperture 34 in collector mirror 26. The beam is oscillatedin the X direction by mirror 28 a and in the Y direction by mirror 28 bgiving rise to a scanning pattern shown schematically at 11. Thereturning beam 32 returns along the reflection path and is directed ontothe detector 40 by the collector mirror 26. It will of course beappreciated that the arrangement is preferably used in conjunction withthe optical assembly shown in FIG. 1 and the exact positioning andorientation of the parts will be apparent to the skilled reader.

FIG. 14 shows an alternative scan engine form-factor and ergonomichousing variation for incorporation of the scanner described herein orany other suitably dimensioned scanner. In particular the scanner isincorporated into a pen-type housing 600 having a scanning window 602.The pen-type housing 600 is preferably elongate having broad front andrear faces 604,606 and narrow side faces. The scanning window ispreferably provided at the upper end of broad face 604, at the oppositeend to the pen “nib” 612. Scanning can be triggered by one or moretriggers 608,610 provided for example on the side or front face of thepen housing 600. The pen nib 612 can either be a conventional pen or anelectronic pen. Because of the broad faces the arrangement easily housesa scanner module of the type described herein. In addition thepositioning of the window 602 allows ergonomic scanning and thepositioning of a plurality of triggers allows left or right handed usersto use the scanner with ease. It will be seen that the broad rear face606 of the housing 600 contacts the user's palm in reading mode forcomfort and ease of use whilst in the writing mode the narrow side facecontacts the user's palm, so that the arrangement can be used normallyas a pen.

It will be understood that each of the features described above, or twoor more together, may find a useful application in other types ofscanners and bar code readers differing from the types described above.

While the invention has been illustrated and described as embodied in ascan module for an electro-optical scanner, it is not intended to belimited to the details shown, since various modifications and structuralchanges may be made without departing in any way from the spirit andscope of the present invention. In particular it will be recognised thatfeatures described in relation to one embodiment can be incorporatedinto other embodiments as appropriate in a manner that will be apparentto the skilled reader.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims. What is claimed as new and desired to be protected byLetters Patent is set forth in the appended claims.

We claim:
 1. A reader for electro-optically reading indicia, comprising:a) a housing containing electro-optical components for scanning theindicia to be read; b) a handle on the housing for enabling a user tohold the housing during reading in a hand-held mode of operation; and c)a base for supporting the housing on a support surface during reading ina hands-free mode of operation, the base being irremovably connected tothe handle during both the hand-held and the hands-free modes ofoperation.
 2. The reader of claim 1, wherein the base is pivotablyconnected to the handle.
 3. The reader of claim 1, wherein the base hasa generally planar face for making surface area contact with the supportsurface in the hands-free mode.
 4. The reader of claim 1, wherein thehousing has opposite sides, and wherein the base extends past both ofthe sides of the housing.
 5. The reader of claim 1, wherein the housingand the base are located at opposite end regions of the handle.
 6. Thereader of claim 1, and further comprising a mode indicator forindicating the mode of operation.
 7. The reader of claim 1, wherein thehandle extends along a longitudinal direction, and wherein the base ispivotably connected to the handle for movement about a pivot axis thatextends perpendicularly to the longitudinal direction.
 8. The reader ofclaim 7, wherein the handle has leg portions spaced apart along thepivot axis and bounding a cavity, and wherein the base has a projectionextending along the longitudinal direction and received in the cavity.9. The reader of claim 1, and further comprising a mode selector on thereader for selecting the mode of operation.
 10. The reader of claim 9,wherein the base has a generally planar face on which the housing restsin the hands-free mode, and wherein the mode selector is a switchlocated on the face and actuatable between states which correspond tothe modes of operation.
 11. The reader of claim 10, wherein the switchis operatively connected to one of the components, and is actuated to ahands-free state in which said one component enables the hands-freemode, and is actuated to a hand-held state in which said one componentenables the hand-held mode, and wherein the actuation of the switch tothe hand-held state is initiated upon removal of the base from thesupport surface.
 12. The reader of claim 11, and further comprising atrigger for initiating the reading during the hand-held mode; andwherein the switch activates the trigger in the hand-held state, anddeactivates the trigger in the hands-free state.
 13. The reader of claim1, wherein the components include a light source for directing a lightbeam at the indicia, a light sensor having a field of view and operativefor detecting light reflected from the indicia, and a scanner forscanning at least one of the light beam and the field of view in a scanover the indicia.
 14. The reader of claim 13, and further comprising awindow on the housing and through which the light beam and the reflectedlight pass.
 15. A method of electro-optically reading indicia,comprising the steps of: a) providing a handle on a housing containingelectro-optical components for scanning the indicia to be read; b)holding the handle in a user's hand to scan the indicia in a hand-heldmode of operation; c) supporting the housing on a support surface toscan the indicia in a hands-free mode of operation; and d) irremovablyconnecting a base to the handle during both the hand-held and thehands-free modes of operation.
 16. The method of claim 15, wherein theconnecting step is performed by pivotably connecting the base to thehandle.
 17. The method of claim 15, and further comprising the step ofselecting the hand-held mode by performing the holding step, and thestep of selecting the hands-free mode by performing the supporting step.18. The method of claim 15, and further comprising the step ofindicating the mode of operation to the user.